Synthetic routes to sesquiterpene lactones with tumor inhibitory properties will be explored. A number of model systems will be examined with a view to developing efficient reaction sequences leading to the basic structural features of these natural tumor inhibitors. In this connection, new fragmentation schemes for the formation of medium ring olefins and lactones will be attempted. Further aspects of hydroazulene lactone synthesis via solvolysis of cyclopropylcarbinyl systems will be investigated.